Soundsnap - Shutterstock for sound effects
Audio Hero - Over 250,000 royalty free music & sound effects for videos
SoundBetter - Marketplace for musicians and music production professionals
TunePocket - Download 11,000+ royalty free music tracks and sound FX. Buy once, use forever. New music added daily. Save over 50% compared to most popular similar services. Incredible value!
Kapwing - Collaborative video editor for modern creative teams
Free Music Archive - Interactive library of high-quality, legal audio downloads